Various materials made from phosphonitrilic chlorides are useful as fire retardants; U.S. Pat. Nos. 3,455,713, 3,505,087 and 3,532,526.
So far as is known, materials made by the process of this invention have not been heretofore described.
Polydichlorophosphazene linked by a P--O--P bond is depicted on
Page 138 of H. R. Allcock, Phosphorus-Nitrogen Compounds, Academic Press, New York, New York (1972), and PA0 Page 317 of J. R. Van Wazer, Phosphorus and Its Compounds, I Interscience Publishers, Inc., New York, New York (1958). PA0 reacting ammonia with phosphorus and chlorine, U.S. Pat. No. 3,658,487, and PA0 reacting phosphorus trichloride, chlorine, and ammonium chloride; U.S. Pat. No. 3,359, 080.
Polymers having P--O--P bonds made by a different process are described on pages 97-8 of Chemical Week, Feb. 20, 1965.
Unfortunately, the phosphazene fire retardants of the prior art which are used to flame retard cellulosic materials, such as rayon, suffer from the disadvantage of washing out of the final textile fabric. So far as is known, prior art phosphazene fire retardants, except at high loading usually greater than 26 weight percent, have been unable to pass the stringent requirements of Federal Standards, for example, the Children's Sleepwear Standard (DOC FF 3-71) published in Federal Register, Vol. 36, No. 146, pp. 14062-14066, on July 29, 1971. Now for the first time, phosphazene fire retardants according to this invention which are used to flame retard rayon not only pass the Children's Sleepwear Standard, but do so at concentrations which are commercially acceptable. The phosphazenes of this invention do not adversely affect other advantageous properties of rayon.